You should not be using pb in your post workout shake, pb has a lot of fat, which will slow digestion of both carbs and protien post workout.
If your going to use pb, I would suggest that for your morning shake, or other meal replacement shakes, but not pre or post. As for the type, I would use what you have, but switch to natty when your done with it. It isnt so much a trans-fat issue, as it is a sugar issue. Pb like jiff adds a decent amount of sugar to make it sweet, IMO natty is sweet enough as is, and you dont need the added sugar.
I don't do this for my family, my friends, women, accolades, pride, or ego. I do it for me and no one else, its just part of who I am.